<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
        <ul class="js_content ui_content">
            <li>1</li>
            <li>2</li>
            <li>3</li>
        </ul>
	</body>
    <script>
    /*事件委托好处：1，不用循环那么多元素再一个个绑定 2，新添加的元素也能绑定到函数*/
        (function(){
            var ndContent = document.querySelector('.js_content');
            ndContent.addEventListener('click',function(e){
                var target = e.target;
                if(target.tagName === "LI"){
                    alert(target.innerText);
                }
            });
        })()
    </script>
</html>